For many years voice telephone service was implemented over a circuit switched network commonly known as the public switched telephone network (PSTN) and controlled by a local telephone service provider. In such systems, the analog electrical signals representing the conversation are transmitted between the two telephone handsets on a dedicated twisted-pair-copper-wire circuit. More specifically, each telephone handset is coupled to a local switching station on a dedicated pair of copper wires known as a subscriber loop. When a telephone call is placed, the circuit is completed by dynamically coupling each subscriber loop to a dedicated pair of copper wires between the two switching stations.
In a separate field of technology, the internet Protocols have facilitated widespread deployment of IP compliant packet switched networks for transferring of data between devices. When a device is coupled to an IP compliant network, it is assigned an IP address. Typically, the IP address, along with other required IP networking information, is provided to the device by a DHCP server.
Once the device obtains an IP address and the required IP networking information, the IP address is used to route IP packets between the device and other devices coupled to the internet.
Because of the limited number of IP addresses available, certain blocks of IP addresses, referred to as private network addresses, are routable only on the IP subnet on which the device is coupled. A network address translation server (NAT) is used to couple the subnet to the internet in a manner that enables all of the devices on the subnet to share the globally routable IP address(es) assigned to the NAT server. In this situation, the DCHP server provides an IP address to a device must be located on the same subnet as the device.
More recently, voice telephone service has been implemented over the internet. Advances in the speed of internet data transmissions and internet bandwidth have made it possible for telephone conversations to be communicated using the internet's packet switched architecture and the TCP/IP and UDP/IP protocols.
To promote the wide spread use of internet telephony, the International Telecommunication Union (ITU) had developed the H.323 set of standards and the internet Engineering Task Force (IETF) has developed the Session Initiation Protocol (SIP) and the Multi-Media Gateway Control Protocol (MGCP).
The above described protocols may be used to initiate an internet telephony session between two IP devices utilizing each devices IP address. Several problems exist with integrating internet telephony with traditional circuit switched telephony.
First, people are accustomed to initiating a telephone call using a telephone number that is permanently assigned to the called station. A call placed to an internet telephony device must be initiated using the devices IP address. An IP address of a device is subject to frequent change and, if the device is located on a local area network, the device's IP address may be a private network IP address that is not even routable on the internet. There must exist a solution for enabling a call to be placed to an internet telephony device without entry of the devices IP address at the calling station.
Secondly, a call placed from an internet telephony device may be placed to a called station served by the PSTN. There must exist a solution for enabling a call placed by an internet telephony device to be coupled to the PSTN.
Thirdly, a call placed from a PSTN station may be placed to an internet telephony device. There must exist a solution for enabling a call placed by a PSTN station to be coupled to the internet and routed to the internet telephony device.
To solve these solutions, an internet telephony service provider may assign a PSTN routable number to each internet telephony device. The telephone number routes on the PSTN to a gateway controlled by the telephony service provider. Various servers (e.g. soft switches, call agents, proxy servers, trunking gateways, signaling gateways, accounting servers, etc) facilitate set up, maintenance, and usage tracking for both inbound and outbound calls of the internet telephony device over the internet.
When an internet telephony device is coupled to an IP network, not only does the internet telephony device need to obtain an IP address and the required networking configuration provided by a DHCP server, but the device also needs to obtain internet telephony service provider contact information so that the device may establish services with the internet telephony services provider's provisioning servers such as an SNMP server, a TFTP server, and a SYSLOG server. These servers in turn provide class and device configuration which enable the device to place and receive internet telephony calls through the internet telephony service provider's signaling and gateway servers.
Existing provisioning systems, such as the provisioning system proposed by Cable Television Laboratories in its specification entitled “PacketCable MTA Device Provisioning Specification” numbered PKT-SP-PROV-106-030415, propose using DHCP options such that a DHCP server can provide the internet telephony service provider contact information. For example, DHCP options enable a DHCP server to provide a fully qualified domain name for the internet telephony service provider's SNMP server and an IP address for the internet telephony service provider's SYSLOG server.
There exist several problems with DHCP provisioning. First, the telephony service provider may not control the DHCP server from which the internet telephony device obtains its configuration.
In this case, the communication service provider has no control over whether the DHCP server provides the options or, if the options are provided, whether the domain names and IP addresses provided are correct. This can lead to one of several results including in-operation of the internet telephony device or unintended operation of the internet telephony device with another communication service provider's system.
What is needed is a system for identifying and contacting an internet telephony service provider's provisioning servers over a packet switched network that does not suffer the disadvantages of the above described systems.